Leigh Van Valen
American biologist (1935–2010)
Leigh Van Valen (August 12, 1935 – October 16, 2010) was an American evolutionary biologist. At the time of his death, he was professor emeritus in the Department of Ecology and Evolution at the University of Chicago.
Research and interests
Amongst other work, Van Valen's proposed "Law of Extinction", known as Van Valen's law, drew upon the apparent constant probability (as opposed to rate) of extinction in families of related organisms, based on data compiled from existing literature on the duration of tens of thousands of genera throughout the fossil record. Van Valen proposed the Red Queen hypothesis (1973), as an explanatory tangent to the Law of Extinction. The Red Queen hypothesis captures the idea that there is a constant 'arms race' between co-evolving species. Its name is a reference to the Red Queen's race in Lewis Carroll's Through the Looking-Glass, in which the chess board moves such that Alice must continue running just to stay in the same place.
Van Valen also defined the Ecological Species Concept in 1976, in contrast to Ernst Mayr's Biological Species Concept. In 1991, he proposed that HeLa cells be defined as a new species, which was named Helacyton gartleri.
Van Valen originated the concept of fuzzy sets, prior to the formalization of this concept by L.A. Zadeh. He was the founding editor of the journal Evolutionary Theory, which he printed on simple paper stock under the motto, "Substance over form."
He was also interested in fields outside biology, including measure theory, probability theory, logic, thermodynamics, epistemology and the philosophy of science.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 8, 2026. The linked authority identifier is Q1815056. VIAF identifies the subject as 49073632. The Library of Congress control number is nr89014024. 3 of 3 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1935, 2010, 1973 and 1976.
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This entry incorporates text from “Leigh Van Valen” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.